A conventional work machine such as a hydraulic shovel executes various tasks using a work device and also turns the upper revolving body with respect to the lower traveling body by operating hydraulic actuators such as a hydraulic cylinder and a hydraulic motor with hydraulic oil that is discharged from a hydraulic pump driven by the engine.
In some cases the operator of such work machine does not need to perform leveling (smoothing of the ground) or crane operations using the maximum power of the hydraulic system or at the maximum speed thereof. In such a case, while the power required in the hydraulic system is low because the amount of lever operation by the operator is small and the speeds of the hydraulic actuators are low, the energy loss of the hydraulic system is high because the amount of hydraulic oil to be bled off to a tank through, for example, a control valve is high or the energy loss is high in the pump due to the lowered efficiency. Therefore, the hydraulic system is required to be used at its efficient point in accordance with the work amounts of the hydraulic actuators associated with the operation of the lever by the operator.
For example, a configuration has been known in which each task is identified using fuzzy inference based on the amount of lever operation by the operator [(see, for example, PTL 1 to PTL 5)]. However, the known configurations aim to identify the type of task and improve the operability merely by controlling pump flow rates or changing the state of an engine auto deceleration control, so the use of the hydraulic system at its efficient point is not taken into consideration.